Economic importance of algae with special reference to food, feed and major uses in industry
Economic importance of algae:-
A. Useful activities:-
1. Primary Producers:-
> Algae are the main Oxygen producers in aquatic areas.
> They are also useful in decreasing water pollution by realizing Oxygen.
> 10% of photosynthesis is occurred by the algae in total photosynthesis quantity.
2. Algae as food:-
> Algae species are used as food in several countries in several forms.
> Algae species have proteins, vitamins (A, B, C and E), lipids, and minerals.
> Laminaria species is the important edible seaweed in Japan and the food item ‘Kombu’ is prepared
from it.
> ‘Aonori’ from Monostroma; ‘Asakusa Nori’ from Porphyra are prepared in different countries.
> Porphyra has 35% protein, 45% carbohydrates, Vitamins B and C and Niacin.
> Nostoc is used as food material in South America.
3. Algae as fodder for cattle:-
> Rhodymenia palmate is used as food for sheeps in Narvey.
> The most widely used microalgae for protein-rich feed supplements include species of Chlorella, Arthrospira, Dunaliella, Tetraselmis, Phaeodactylum, Skeletonema, and Scenedesmus.
> Cultivation of Spirulina is gaining importance as feed for fish, poultry and cattle.
4. Algae as fertilizers:-
> Blue-green algae are treated as biofertilizers from olden days.
> Nostoc, Oscillatoria, Scytonema, Spirulina, etc. are used as fertilizers to rice fields.
> All these algae are fixed the atmosphere Nitrogen in to ground.
5. Algae in Pisi culture:-
> Sea algae are used as food for fishes. So they play an important role in Pisi culture.
> Some green-algae, Diatoms, some blue-green algae are used as food material to fishes.
> These are also making the water clean, by realizing Oxygen.
6. Alginates:-
> Alginates are the salts of alginic acid found in the cell wall of phaeophyceae.
> Alginates are extracted from Fucus, Laminaria, Macrocystis and Ecklonia.
> Alginates are used in the preparation of flameproof fibrics, plastics, paints, gauze material in surgical dressing, soups, ice creams etc.
7. Algea in industry:-
a. Iodine:-
> Iodine industry is mainly depended upon algae.
> Algae belonging to Phaeophyceae, like Laminaria, Ecklonia, Eisenia, etc. are used in the industry to prepare Iodine in industries.
> Phyllophora is used to prepare Iodine in Russia.
b. Agar-Agar:-
> Agar-agar is a jelly like substance of great economic value.
> It is obtained from certain red algae like Gelidium, Graciliaria and Gigartina.
> Agar is used as a culture medium for growing callus in tissue culture.
c. Carrageenin:-
> It is extracted from cell walls of red algae like Chondrus and Gigartina.
> It is a polysaccharide esterfied with sulphate.
> It is used as emulsifier in pharmaceutical industry and also in textile, leather, cosmetics and brewing industries.
d. Diatomite:-
> Diatoms deposits at marine and fresh water areas.
> Diatoms are rich with silica. It is called as diatomite.
> diatomite is used in the preparation of Dynamite in olden days.
> But now diatomite is used in different industries like glass, metal polishing, paints, tooth pasts, soups, etc.
e. Minerals:-
> The brown sea weeds popularly called as kelpyield potash, soda, and iodine.
> Some sea weeds are rich source of iron, zinc, copper, manganese and boron.
> Bromine is extracted from red algae such as Polysiphonia and Rhodymenia.
f. Funori:-
> It is a type of glue obtained from a red alga Gloipeltis furcata.
> It is used as an adhesive as well as sizing agent for paper and cloth.
> Chemically it is similar to agar-agar except that there is no sulphate ester group.
8. Algae in reclamation of alkaline or Usar soils:-
> Our country has more number of alkaline soils or sterile soils.
> Blue-green algae like Nostoc, Oscillatoria, Scytonema, Spirulina are modified the soils in to fertile soils. Because they fixed Nitrogen in to soil.
> Nearly they fixed 400 K.g. of Nitrogen per year.
> Soil erosion is also reduced by these algae.
9. Antibiotics and Medicines:-
> Antibiotic Chlorellin, obtained from Chlorella is effective against a number of pathogenic bacteria.
> Extracts from Cladophora, Lyngbya can kill pathogenic Pseudomonas and Mycobacterium.
> Laminaria is used as one of the modern tools for abortion.
> Seaweeds have beneficial effect on gall bladders, pancreas, kidneys, uterus and thyroid glands.
10. Role of Algae in Sewage Disposal:-
> Some species like Chlamydomonas, Scenedesmus, Chlorella, Pondorhina, Euridina, etc are living in sewage water.
> They are mainly useful to clean the water by realizing Oxygen.
> They also modified the carbonate material in the water into N, P, K fertilizers.
11. Algae as research material:-
> In biological research algae are useful because of their rapid growth, brief life span and easy mode of cultivation.
> Chlorella, Scenedesmus and Anacystis are used in investigations in photosynthesis. Blue-green
algae are used in studies on nitrogen fixation.
> Researches in Genetics and Cytology are carried out on Acetabularia.
12. Algae in Space:- Chlorella and Synechococcus are finding application in space ships and nuclear submarines as oxygen regenerating and food and water recycling organisms.
B. Harmful activities:-
> Some algae species like Microcystis, Lyngbya are develop water blooms in water areas. They secrete toxic materials into water. That they polluted the water.
> The algae, Cephaleuros virescence causes for red rust tea in tea plant.
> Some algae species are caused for some skin diseases.
> Dianophlagellate is caused for the death of fishes in water.
> Because of their production of oxygen and their role in the food web, algae are normally beneficial to aquatic life.
> However, a bloom (a large and sudden growth in the population of phytoplankton) can cause the death of many fish.
> In most cases fish die because the decomposition of large amounts of algae depletes the oxygen in the
water.
> Phytoplankton that produce blooms called red tides produce toxins that kill fish directly. These toxins are also poisonous to humans; persons who eat shellfish contaminated with the toxins can become seriously ill.
> Most blooms occur in bodies of water that have been polluted with sewage or with runoff containing organic substances such as fertilizers.